M_CAN_PSR field descriptions (continued)
Field Description
29–31
LEC
Last Error Code
The LEC indicates the type of the last error to occur on the CAN bus. This field will be cleared to 0 when a
message has been transferred (reception or transmission) without error.
NOTE: This field is set by a read operation.
000 Error: No error occurred since LEC has been reset by successful reception or transmission
001 Stuff Error: More than 5 equal bits in a sequence have occurred in a part of a received message
where this is not allowed
010 Form Error: A fixed format part of a received frame has the wrong format
011 AckError: The message transmitted by the M_CAN was not acknowledged by another node
100 Bit1Error: During the transmission of a message (with the exception of the arbitration field), the
device wanted to send a recessive level (bit of logical value 1), but the monitored bus value was
dominant
101 Bit0Error: During the transmission of a message (or acknowledge bit, or active error flag, or
overload flag), the device wanted to send a dominant level (data or identifier bit logical value 0), but
the monitored bus value was recessive. During Bus_Off recovery this status is set each time a
sequence of 11 recessive bits has been monitored. This enables the CPU to monitor the proceeding
of the Bus_Off recovery sequence (indicating the bus is not stuck at dominant or continuously
disturbed)
110 CRCError: The CRC check sum of a received message was incorrect. The CRC of an incoming
message does not match with the CRC calculated from the received data
111 NoChange: Any read access to the Protocol Status Register re-initializes the LEC to 7. When the
LEC shows the value 7, no CAN bus event was detected since the last CPU read access to the
Protocol Status Register
Memory Map and Register Description
MPC5777C Reference Manual Addendum, Rev. 1, 12/2015
44 Freescale Semiconductor, Inc.
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